This invention relates generally to inflation devices such as for the inflation of an airbag and, more particularly, to an airbag inflator that can supply or provide inflation gas at various quantities and/or selected or adaptive rates.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an “airbag cushion,” that is inflated or expanded with gas when the vehicle encounters sudden deceleration, such as in the event of a collision. In such systems, the airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. The airbag cushion is designed to inflate into a location within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, instrument panel or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior. Upon actuation of the system, the, cushion begins to be inflated or expanded, in a matter of no more than a few milliseconds, with gas produced or supplied by a device commonly referred to as an “inflator.”
Various types of airbag inflator devices have been disclosed in the art for the inflation of airbag cushions such as used in inflatable restraint systems. One such inflator device, generally known as a hybrid airbag inflator or hybrid gas generator, uses high temperature reaction products, typically also including additional gas products, generated by the reaction of a reactive material, to increase the gas pressure within the inflator, rupturing a rupturable seal and inflating one or more airbag cushions. Such gas-filled hybrid inflators typically provide a relatively high airbag inflation rate. In some cases, the stored and pressurized gas may include or form an oxidizing gas to assist in more fully converting the reaction products generated by the reaction of the reactive material, to compounds such as carbon dioxide and water.
Often such inflator devices also include an initiator, such as a squib, and an igniter composition to actuate the reactive material. In practice, upon receipt of an appropriate triggering signal from a crash or deceleration sensor, the initiator activates causing the rapid combustion of the igniter composition, which in turn actuates the reactive material. The igniter composition may be incorporated in the initiator in various forms such as a granular material.
The size, shape, and components of airbag inflators can vary depending on the vehicle and where in the vehicle the airbag inflator is used, e.g., driver side or passenger-side. In addition, the size of the reactive material load contained within such an inflator structure is generally predetermined in order to be sufficient to result in desired inflation of the associated airbag cushion upon actuation of the inflator. As will be appreciated, the incorporation and use of a different sized inflator are often necessary to change or alter the inflation performance provided by the inflator system. Consequently, significant design changes may be required to permit the incorporation and use of such inflator system between applications requiring or desiring different inflation performances.
In view of possibly varying operating conditions and, in turn, possibly varying desired performance characteristics, there is a need and a desire to provide what has been termed an “adaptive” airbag inflator device and a corresponding inflatable restraint system. With an adaptive inflator, output parameters such as one or more of the quantity, supply and rate of production of inflation gas, for example, can be selectively and appropriately varied dependent on selected operating conditions such as ambient temperature, occupant presence or position, seat belt usage and rate of deceleration of the motor vehicle, for example.
Safety restraint airbag cushions are normally sized and shaped to provide a vehicle occupant with desired cushioning protection when such an airbag cushion has been properly deployed. In a typical airbag module assembly, an airbag cushion is normally stored within a reaction canister in an uninflated, folded condition. In practice, an airbag cushion for the protection of a front seat passenger in the event of a vehicular frontal impact is typically of a substantially larger size, e.g., larger volume, than a corresponding airbag cushion for the protection of the vehicle driver. Consequently, an inflator device associated with the inflation of a passenger airbag cushion must typically provide a substantially greater relative volume or amount of inflation gas in a timely and effective manner. However, passenger occupants typically do not maintain a relatively standard traveling position as do vehicle drivers. Due to the variations in passenger positions, it can be desirable that the passenger side airbag deploys at a slower initial rate followed by a subsequent increase in deployment rate. Therefore, the chance of injury due to an out-of-position occupant is decreased. This type of variation in deployment can be obtained through controlled inflation gas output, generally referred to as adaptive inflation gas output.
While such adaptive systems are desirable, they typically require the inclusion of additional components as a part of the associated inflator device. As will be appreciated, the inclusion of such additional components may undesirably increase one or more of the size, cost and weight of the inflator device. In view thereof, it has been difficult to provide an adaptive inflator, and particularly an adaptive hybrid inflator, which will satisfactorily meet the size, cost and weight limitations associated with modern vehicle design, particularly as it pertains to passenger side applications.
Thus, there is a need and a demand for an adaptive inflator device, and more particularly an adaptive hybrid inflator, of relatively simple design and construction and, in turn, comparatively, low or reduced cost. In particular, there is a need and a demand for such an adaptive inflator device which will meet the differing output requirements between various vehicles with a single design.